Hybrid Recirculating/Vented Tumble Dryer With Purposeful Fresh Air Inlet At Drying Chamber

ABSTRACT

A hybrid vented tumble dryer which includes a drying chamber such as a rotatable drum, a heater, a process air fan, a recirculation duct, and a process air circuit configured to recirculate process air through the dryer. The dryer may include first and second drum seal gaskets located between the drum and first and second bulkheads, respectively. In some embodiments, the recirculation duct is in closed fluid communication with the heater. In other embodiments, the process air circuit is configured such that substantially the only fresh air which enters the process air circuit enters directly into the drying chamber prior to passing through the heater, or such that substantially the only fresh air which enters the process air circuit enters the process air circuit, in an airflow direction of the process air moving through the process air circuit, after the heater and before an outlet of the drying chamber.

TECHNICAL FIELD

The present invention relates generally to laundry dryers. In particular, the invention relates to a hybrid vented tumble dryer, i.e., a dryer that recirculates and exhausts drying air.

BACKGROUND

A traditional vented tumble dryer removes moisture from clothing and other articles by drawing heated air across the damp articles placed within a rotating drum. For example, FIG. 1 is schematic of a process air circuit of a traditional vented tumble dryer 100. As schematically depicted in FIG. 1, process air 103 is drawn (by a process air fan 110 located downstream of a drying chamber 108) through a fresh air inlet 101 located at an upstream end of a supply duct 102, across a heater 106 where the process air 103 is heated, and into the drying chamber 108 (e.g., a rotatable drum). Within the drying chamber 108, the heated process air 103 passes across damp articles 112 provided therein thus removing moisture from the tumbling articles 112. The process air 105 is then drawn through a lint filter 114, which serves to remove lint and debris from the process air 105 before it is ultimately exhausted from the dryer 100 at an exhaust duct 116 (typically to an outside of a building in which the dryer 100 is housed). In addition to the heated process air 103 entering the drying chamber 108 via the air inlet 101 provided upstream of the supply duct 102, fresh air 118 (i.e., air located within a cabinet of the vented tumble dryer 100 but which does not pass over the heater 106) may enter the drying chamber 108 due to, e.g., leakage around drum seal gaskets of the rotatable drum. In this regard, the process air 105 leaving the drying chamber 108, which is ultimately exhausted from the dryer 100 via the exhaust duct 116, is a combination of the process air 103 which entered the system at the air inlet 101, and the fresh air 118 which entered the system via, e.g., leakage around the drum seal gaskets of the drying chamber 108. Accordingly, a flow rate of the process air 105 exhausting from the dryer 100 is greater than a flow rate of the process air 103 entering the system at the air inlet 101.

This traditional vented tumble dryer 100 is not a very efficient machine. Specifically, and particularly when a small load of articles 112 is placed within the drying chamber 108 to be dried, the heated process air 103 entering the drying chamber 108 may not interact optimally with the damp articles 112 for removing moisture therefrom before it is exhausted from the dryer 100 at the exhaust duct 116. Accordingly, when the process air 105 is exhausted from the dryer 100, energy used to heat the process air 105 (which has additional drying potential) is wasted.

In an effort to thus improve the efficiency of the traditional vented tumble dryer 100, some dryers recirculate a portion of the process air 105 leaving the drying chamber 108. That is, as discussed, the process air 105 leaving the drying chamber 108 may still hold the potential to absorb additional water. When this process air 105 is recirculated (e.g., directed back into the drying chamber 108), it performs further drying of the articles 112, thus improving the overall efficiency of the machine. These “hybrid” vented tumble dryers (“hybrid” in the sense that a portion of the process air is recirculated and a portion of the process air is exhausted) thus recapture otherwise lost drying potential of the heated process air 103 rather than simply exhausting the entirety of the process air 105 from the system after a single pass.

For example, FIG. 2 is a schematic of a process air circuit of a known hybrid vented tumble dryer 200. As with the traditional vented tumble dryer 100, in the hybrid vented tumble dryer 200, fresh air 218 is drawn by a process air fan 210 through a fresh air inlet 201 provided immediately upstream of a supply duct 202 and mixes with recirculated process air 207 (which, as will be discussed more fully, is directed by a recirculation duct 220 to the fresh air inlet 201 and/or the supply duct 202) forming supply process air 203. The supply process air 203 is drawn through the supply duct 202, across a heater 206, and into a drying chamber 208 where it passes across the tumbling damp articles 212 and mixes with fresh air 218 unintentionally entering the drying chamber 208 via, e.g., leakage at drum seal gaskets of a rotatable drum. The process air 205 (i.e., the combined supply process air 203 and the fresh air 218 entering around the drum seal gaskets of the drum, which has passed over the damp articles 212) is then drawn through a lint filter 214. At this point, a portion of the process air 205 is exhausted to an outside via an exhaust duct 216, while another portion (indicated in FIG. 2 as reference numeral 207) is recirculated (i.e., returned to the air inlet 201 and/or the supply duct 202) via the recirculation duct 220. This recirculated process air 207 is then mixed with the fresh air 218 entering the supply duct 202 via the air inlet 201, and is again drawn across the heater 206, through the drying chamber 208, and across the lint filter 214 as discussed. In that regard, drying potential of the recirculated process air 207 that went unused may be recaptured when the recirculated process air 207 is ultimately reintroduced into the drying chamber 208, and the overall efficiency of the dryer 200 may be increased (as compared to the traditional vented tumble dryer 100).

However, because fresh air 218 enters the system at, e.g., drum seal gaskets or the like at the drying chamber 208, the entirety of the recirculated process air 207 may not actually be reintroduced into the process air circuit at the inlet duct 202. More particularly, the flow rate of the recirculated process air 207 cannot exceed a physical limit fixed by the flow limits of the process air fan 210 and the amount of fresh air 218 which enters the drying chamber 208. This may be better understood with reference to a specific example.

First, returning to the traditional vented tumble dryer 100 in FIG. 1, the process air fan 110 fixes the flow rate of the process air 105 exhausting from the system. For example, the process air fan 110 may be configured to draw the process air 105 through the system (and ultimately exhaust the process air 105 from the system) at 180 m³/h. So, for example, if 80 m³/h of fresh air 118 enters the drying chamber 108 due to, e.g., leakage at the drum seals, then 100 m³/h of fresh air remains to enter the system at the air inlet 101 (i.e., 180 m³/h−80 m³/h=100 m³/h of fresh air entering at the air inlet 101).

When this system is modified into the hybrid vented tumble dryer 200 to improve efficiency as discussed, the flow rate of the process air 205 through the system will nonetheless still be capped by the flow rate of the process air fan 210. So, returning to the example where the process air fan 210 draws 180 m³/h of process air 205 through the system, and 80 m³/h of fresh air 218 enters the drying chamber 208 due to leakage at the drum seal gaskets, the flow rate of the supply process air 203 (i.e., the recirculated process air 207 combined with the fresh air 218 entering the system at the air inlet 201) will be capped at 100 m³/h. In that regard, if the dryer 200 is configured to recirculate the recirculated process air 207 at 100 m³/h or less, then the entirety of the recirculated process air may be reintroduced into the system at the supply duct 202. However, if the dryer 200 is configured such that the recirculated process air 207 is recirculated at a greater flow rate than 100 m³/h, only a maximum of 100 m³/h of that recirculated process air 207 will be reintroduced into the system at the supply duct 202, with the remaining portion of the process air 207 escaping from the system into an interior of a cabinet of the dryer 200 through the air inlet 201 (schematically represented by escaping process air 209 in FIG. 2).

Accordingly, and returning to the above example, if the process air fan 210 is configured to draw 180 m³/h of process air 205 and the hybrid vented tumble dryer 200 is configured to recirculate, e.g., 130 m³/h of the process air 207, but 80 m³/h of fresh air 218 enters the drying chamber 208 via leakage at the drum seal gaskets, only 100 m³/h of the recirculated process air 207 will actually be pulled through the supply duct 202. The remaining 30 m³/h of the recirculated process air 207 will escape to (and may ultimately condense within) an interior of the cabinet of the dryer 200. Accordingly, the interior of the dryer 200 may be damaged.

Ideally, the hybrid vented tumble dryer 200 is designed such that a near maximum amount of process air 207 is recirculated (which still has the potential to absorb additional water) while preventing any portion of this recirculated process air 207 escaping into the interior of the dryer's cabinet immediately upstream of the supply duct 202 at the air inlet 201. However, over time the drum seal gaskets of the dryer 200 may begin to wear, allowing more fresh air 218 to enter the system at the drying chamber. In this regard, even if the dryer 200 is originally designed such that no portion of the recirculated process air 207 escapes into a cabinet at the air inlet 201, over time the originally designed flow rate of the recirculation process air 207 may be too high. That is, with the additional fresh air 218 entering around the worn drum seal gaskets, the originally configured flow rate of the recirculated process air 207 may be too high for the flow rate capped by the process air fan 210, and accordingly a portion of the recirculated process air 207 may escape to the interior of the hybrid vented tumble dryer 200 at the air inlet 201.

Accordingly, there remains a need for a vented tumble dryer which exhibits improved efficiency over a traditional vented tumble dryer, and which overcomes one or more of the above-discussed deficiencies associated with recirculating a portion of the process air. More particularly, there remains a need for a hybrid vented tumble dryer which recirculates a portion of the process air in order to increase efficiency, but which is more effective in preventing the recirculated process air from escaping into an interior of the hybrid vented tumble dryer.

BRIEF SUMMARY OF SELECTED INVENTIVE ASPECTS

The instant disclosure is directed to a hybrid vented tumble dryer which overcomes one or more of the above-discussed deficiencies of known hybrid vented tumble dryers.

According to a first aspect of the invention, a hybrid vented tumble dryer includes a drying chamber, a heater configured to heat process air entering the drying chamber, a process air fan configured to draw the process air through the drying chamber, an exhaust duct configured to exhaust a first portion of the process air from the drying chamber, a recirculation duct configured to direct a second portion of the process air from the drying chamber to the heater, and a process air circuit configured to recirculate the process air through the hybrid vented tumble dryer. The process air circuit is defined at least in part by the drying chamber, the heater, the process air fan, and the recirculation duct. Further, the process air circuit is configured such that the drying chamber is located between the heater and the process air fan such that the process air leaving the heater passes through the drying chamber before the process air reaches the process air fan, and the recirculation duct is located between the process air fan and the heater such that the second portion of the process air leaving the process air fan passes through the recirculation duct before the process air reaches the heater. The process air circuit is also configured such that substantially the only fresh air which enters the process air circuit enters directly into the drying chamber prior to passing through the heater.

According to another aspect of the invention, the drying chamber of the hybrid vented tumble dryer includes an inlet and an outlet with the process air moving through the drying chamber entering at the inlet and exiting at the outlet. In such embodiments, substantially the only fresh air that enters the process air circuit enters the process air circuit, in an airflow direction of the process air moving through the process air circuit, at a location after the heater but before the outlet of the drying chamber.

According to still another aspect of the invention, the hybrid vented tumble dryer includes a rotatable drum, a first and second bulkhead, and a first and second drum seal gasket. The first drum seal gasket is located between the rotatable drum and the first bulkhead in a non-airtight manner and the second drum seal gasket is located between the rotatable drum and the second bulkhead in the non-airtight manner such that the fresh air can enter the rotatable drum at the first and second drum seal gaskets. In such embodiments, the recirculation duct is in closed fluid communication with the heater.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features, aspects, and advantages of the invention will be fully apparent and understood from the following detailed description, taken together with the appended drawings, wherein:

FIG. 1 is a schematic of a process air circuit of a traditional vented tumble dryer.

FIG. 2 is a schematic of a process air circuit of a known-type hybrid vented tumble dryer.

FIG. 3 is a schematic of a process air circuit of a hybrid vented tumble dryer according to aspects of the invention.

FIG. 4 is a perspective view of a first embodiment of a hybrid vented tumble dryer, with a cabinet and other components removed in order to better illustrate a recirculation air channel therein.

FIG. 5 is a perspective view of a basement portion of the hybrid vented tumble dryer depicted in FIG. 4.

FIG. 6 is a perspective view of a second embodiment of a hybrid vented tumble dryer, with the cabinet and other components removed in order to better illustrate a recirculation air channel therein.

FIG. 7 is a perspective view of the interior components of the hybrid tumble dryer depicted in FIG. 6, and further illustrating a basement portion of the same.

FIG. 8 is a perspective view of the basement portion of the hybrid vented tumble dryer depicted in FIG. 7.

FIG. 9 is a perspective view of a hybrid vented tumble dryer that could be of the type depicted in either FIG. 4 or FIG. 6, with portions of the cabinet removed to in order to illustrate interior components of the same.

FIG. 10 is a top view of the hybrid vented tumble dryer depicted in FIG. 9, with portions of the cabinet removed to in order to illustrate interior components of the same.

FIG. 11 is an exploded view of front and rear bulkheads and a rotatable drum supported therebetween of the hybrid vented tumble dryer depicted in FIG. 9.

FIG. 12 is an exploded view of the front and rear bulkheads, the rotatable drum, and drum seals of the hybrid vented tumble dryer depicted in FIG. 9.

FIG. 13 is a perspective view of the hybrid vented tumble dryer depicted in FIG. 4, with the cabinet and other components removed in order to better illustrate a recirculation air channel of the hybrid vented tumble dryer, and further including airflow arrows indicating a flow of fresh and recirculated process air into and through the airflow circuit.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

As schematically seen in FIG. 3, in a hybrid vented tumble dryer 300 according to aspects of the invention, process air 307 is drawn (by operation of a process air fan 310) through a supply duct 302, across a heater 306, and into a drying chamber 308. Within the drying chamber 308, the heated process air 307 passes across articles 312 provided therein thus removing moisture from the tumbling articles 312, and mixes with fresh air 318 (i.e., air within a cabinet of the dryer 300 but which is outside of the process air circuit, and which does not pass over the heater 306) entering the drying chamber 308 around, e.g., drum seal gaskets or the like (discussed more fully below). The process air 305 (i.e., the process air 307 mixed with the fresh air 318) is then drawn through a lint filter 314. The flow rate of the process air 305 leaving the drying chamber 308 is thus greater than the flow rate of the heated process air 307 entering the drying chamber 308, due to the heated process air 307 mixing with the fresh air 318 at the drying chamber 308. This process air 305, which still has some drying potential (as previously discussed), is then split, with a first portion ultimately exhausted from the dryer 300 at an exhaust duct 316 (typically to an outside of the building in which the vented tumble dryer is housed), and a second portion (more particularly, the recirculated process air 307) recirculated via a recirculation duct 320.

The recirculated process air 307 is then reintroduced to the supply duct 302, and then flows again through the process air circuit as described. Notably, however, the recirculated process air 307 is not mixed with fresh air at the supply duct 302 before passing across the heater 306. More specifically, unlike the hybrid vented tumble dryer 200 discussed above in connection with FIG. 2, the dryer 300 does not include a fresh air inlet (e.g., air inlet 201) immediately upstream of the heater 306. Rather, in accordance with an aspect of the invention, the fresh air 318 which enters the process air circuit is substantially only the fresh air 318 that enters at the drying chamber 308 around, e.g., the rotational drum seal gaskets or the like. In this regard, the dryer 300 may be operated at or near maximum efficiency (i.e., a maximum amount of recirculated process air 307 provided to the supply duct 302) without concern that any portion thereof may leak into an interior of the cabinet, because there is no open fresh air inlet provided immediately upstream of the heater 306 from which the recirculated process air 307 can escape. Accordingly, damage to interior components of the dryer 300 caused by the moist process air escaping into the cabinet can be avoided.

The above may be better understood with reference to the example embodiments of the hybrid vented tumble dryer depicted in FIGS. 4-13. First, FIGS. 4, 5, and 13 depict a first embodiment of an exemplary hybrid vented tumble dryer 400. The dryer 400 includes a recirculation duct 420 which is fluidly connected to a heater canister 402 as one suitable example of a supply duct 302 (internally including, e.g., a resistance-type heater 406) such that no fresh air enters the process air circuit immediately upstream of the heater 406 (i.e., the dryer 400 does not include an air inlet such as the fresh air inlet 201 discussed in connection with FIG. 2). The heater canister 402 is fluidly connected to a rear manifold 424 provided at a rear end of a rotatable drum 426, and the rear manifold 424 is in fluid communication with a drum inlet 1102 (FIG. 11) provided in a rear bulkhead 428 of the dryer 400. In this regard, a first part of a process air circuit is formed from the heater canister 402, through the rear manifold 424 and the drum inlet 1102, and into the drying chamber 408.

The rotatable drum 426 is rotatably supported between the rear bulkhead 428 and a front bulkhead 430. More particularly, and as best seen in FIGS. 11 and 12, the bulkheads 428, 430 each provide a respective circular track 1106, 1104, with each track 1106, 1104 configured to receive a corresponding end 1110, 1108 of the rotatable drum 426 such that, during operation, the drum 426 rotates about a horizontal axis with respect to the bulkheads 428, 430 (as will be discussed more fully in connection with FIGS. 5, 9, and 10). For example, the back end 1110 of the rotatable drum 426 is received in the circular track 1106 (which may be, e.g., stamped in the rear bulkhead 428), and is rotatably supported by a plurality (e.g., three) of rear rollers 400. Similarly, the front end 1108 of the rotatable drum 426 is received in the circular track 1104 (which may be, e.g., stamped in the front bulkhead 430), and is rotatably supported by a plurality (e.g., two) of front rollers 442. The front bulkhead 430 forms an access opening 432 which is located behind an access door (not shown) provided on a cabinet of the dryer 400. The front bulkhead 430 further includes an opening for removably receiving the lint filter 414. Accordingly, during use, a user of the dryer 400 may access the drying chamber 408 via the access opening 432 (in order to insert or remove the articles 312) and/or access the lint filter 414 by simply opening the access door provided on the cabinet of the dryer 400.

The rotatable drum 426 is configured to be rotated by a motor 502 (FIG. 5) provided in a basement portion of the dryer 400 in order to tumble the articles 312 provided therein. The motor 502 rotatably drives the drum 426 via a belt 902 which wraps around a drive wheel and the outer circumference of the drum 426 (as seen in in FIGS. 9 and 10) in a conventional manner. Referring to FIGS. 11 and 12, a front drum seal gasket 434 is provided between the rotatable drum 426 and the front bulkhead 430, and a rear drum seal gasket 436 is provided between the rotatable drum 426 and the rear bulkhead 428. The drum seal gaskets 434 and 436 may be conventional wear-resistant gaskets configured to allow low-friction rotation of the drum 426 on the front and rear bulkheads 430, 428, while also significantly restricting (although not completely blocking) airflow at the sliding interfaces. In some embodiments, the drum seal gaskets 434 and 436 may include, e.g., polyester and/or recycled wool. Additionally or alternatively, in some embodiments the drum seal gaskets 434 and 436 may include polyurethane (PU), ethylene propylene diene monomer (EPDM) rubber, and/or polytetrafluoroethylene (PTFE), such as TEFLON® or the like.

As discussed, and referring to FIGS. 4 and 5, an opening is provided in the front bulkhead 430 such that the lint filter 414 can be removably inserted therein. This opening is in fluid communication with a front manifold 438, which in turn is in fluid communication with the process air fan 410. The process air fan 410 is located in the basement portion of the dryer 400 (i.e., below the rotatable drum 426) and fluidly connects the front manifold 438 with the recirculation duct 420 and the exhaust duct 416. Accordingly, a second portion of the process air circuit is formed from the drying chamber 408, through the opening in the front bulkhead 430 (and thus through the lint filer 414), through the front manifold 438 and the process air fan 410, and ultimately into one of the exhaust duct 416 and the recirculation duct 420.

In the embodiment depicted in FIGS. 4, 5, and 13, the recirculation duct 420 splits off from the exhaust duct 416. The recirculation duct 420 extends at a significant reverse angle with respect to the airflow direction of the process air 305 exhausting from the dryer 400, before turning generally vertically towards the heater canister 402. By providing the recirculation duct 420 in such a configuration, an appropriate amount of the process air 305 can be recirculated throughout the dryer 400, limiting the influence of dynamic pressure on the amount of air entering the recirculation duct 420. This is described in more detail in commonly owned U.S. patent application Ser. No. 13/437,499, filed Apr. 2, 2012, and entitled “Dryer with Air Recirculation Subassembly” (published as US 2013/0255098), which is hereby incorporated by reference in its entirety. Further (and as discussed in more detail in US 2013/0255098), the exhaust duct 416 and/or the recirculation duct 420 may include one or more recirculation air filters (not shown) mounted at or near a junction of the exhaust duct 416 and the recirculation duct 420, to remove residual lint or debris from the recirculated process air 307 before it is passes again through the heater canister 402.

FIGS. 6-8 depict another suitable configuration of a hybrid vented tumble dryer 600 including a recirculation duct 620 and which does not include an air inlet immediately upstream of the heater canister 402. In describing the dryer 600 depicted in FIGS. 6-8, like numerals indicate components which are substantially similar to the corresponding components of the dryer 400 depicted in FIGS. 4, 5, and 13, and thus those components will not again be described in detail.

In this embodiment, the recirculation duct 620 includes a removable recirculation air filter 642 (as best seen in FIG. 8) which is configured to remove residual lint or debris from the process air before it is recirculated to the heater canister 402, and which is accessible at the front bulkhead 430 via the access opening 432. Further, the process air circuit downstream of the process air fan 410 splits, with a first portion being defined by the exhaust duct 616, and the second portion being defined by the recirculation duct 620. As best seen in FIG. 6, the exhaust duct 616 extends generally horizontally and rearwardly immediately downstream from the process air fan 410, and the recirculation duct 620 extends generally vertically immediately downstream of the process air fan 410. More particularly, the recirculation duct 620 splits from the exhaust duct 616 and turns upward such that the recirculated process air 307 provided therein is directed towards the recirculation air filter 642.

A recirculation filter housing 640 is provided at an uppermost portion of the recirculation duct 620 which houses the accessible recirculation air filter 642 therein and which has an open end in communication with the access opening 432 (such that a user may remove and clean the recirculation air filter 642 from inside the drying chamber 408 as necessary). The housing 640 removably houses the recirculation air filter 642 such that airflow spacing is provided along one or more sides of the recirculation air filter 642. In this regard, the recirculated process air 307 is directed generally vertically via recirculation duct 620 into the housing 640 and through the recirculation air filter 642, with the recirculated process air 307 exiting the filter 642 along one or more sides of the filter 642. Accordingly, residual lint or debris (i.e., lint or debris that remains in the process air 305 after it passes through the lint filter 414) is removed from the recirculated process air 307 before the recirculated process air 307 is reheated by the heater 406 provided at the heater canister 402, as is described in more detail in commonly owned U.S. patent application Ser. No. 13/912,580, filed Jun. 7, 2013, and entitled “Laundry Dryer with Accessible Recirculation Air Filter,” which is hereby incorporated by reference in its entirety. Finally, the recirculation duct 620 extends generally horizontally and rearwardly downstream of the housing 640, where it fluidly connects to the heater canister 402 in a closed manner, i.e., without any fresh air inlet provided.

In any of the above described embodiments, the recirculation duct 420, 620 is in closed fluid communication with the heater canister 402 (i.e., an open fresh air inlet is not provided immediately upstream of the heater canister 402). Accordingly, and as discussed in connection with FIG. 3, substantially the only fresh air 318 which enters the process air circuit of the hybrid vented tumble dryer 300 is the fresh air 318 which enters at the drying chamber 408 around the drum seal gaskets 434, 436. This will be more readily understood with reference to FIG. 13, which includes airflow arrows overlaying the embodiment of the hybrid vented tumble dryer 400 discussed in connection with FIGS. 4 and 5, in order to more clearly illustrate the flow of the fresh air and the process air through the components of the dryer 400 during operation. Although for simplicity the internal components (and more particularly, the configuration of the recirculation duct 420) of the dryer 400 depicted in FIG. 13 are the same as those depicted in FIGS. 4 and 5, it should be appreciated that the discussion of the airflow path applies equally to other embodiments of the hybrid vented tumble dryer (e.g., the dryer 600 depicted in FIGS. 6-8 or otherwise) with only minor modifications according to the particular structure of the respective recirculation duct 620.

In FIG. 13, the dashed arrows illustrate a flow of the fresh air and the process air moving the process air circuit defined by (in an airflow direction of the recirculating process air) the heater canister 402, the rear manifold 424, the rear bulkhead 428, the rotatable drum 426, the front bulkhead 430, the front manifold 438, the process air fan 410, the exhaust duct 416, and the recirculation duct 420. When flowing through this process air circuit, the recirculated process air 307 is reheated (reheated in the sense that at least a portion of the recirculated process air 307 has already passed over the heater 406) by, e.g., the resistance-type heater 406, and is drawn (via operation of the process air fan 410) through the rear manifold 424, through the drum inlet 1102, and into the drying chamber 408. Once inside the drying chamber 408, the heated process air 307 passes over and removes moisture from damp, tumbling articles 312, thus providing the desired drying of the articles.

The heated process air 307 also mixes with the fresh air 318 (i.e., air that flows relatively freely into and within the cabinet of dryer 300) inside the drying chamber 408. More particularly, the front drum seal gasket 434 and the rear drum seal gasket 436 are configured in a non-airtight manner such that a desired amount of the fresh air 318 can enter the process air circuit at the drum seals. For example, in one suitable embodiment, the gaskets 434, 436 are configured such that airflow spacing is provided between the front gasket 434 and the rotatable drum 426 and/or the front bulkhead 430, and/or such that airflow spacing is provided between the rear gasket 436 and the rotatable drum 426 and/or the rear bulkhead 428. For example, the mechanical properties of the gaskets 434, 436, bulkheads 428, 430, and/or the drum 426 may be configured such that there is less pressure (i.e., sealing action) between the gaskets 434, 436 and the respective end 1108, 1110 of the drum 426 and/or the respective bulkhead 430, 428, allowing a desired amount of fresh air 318 to enter the process air circuit at the drum seal gaskets 434, 436. Additionally or alternatively, the drum 426 may include one or more small gaps and/or holes provided around its circumference, allowing a desired amount of fresh air 318 to enter the process air circuit at the drum seal gaskets 434, 436. In another suitable embodiment, the gaskets 434, 436 may be constructed of an air-permeable material such that the fresh air 318 can enter the drying chamber 402 through the air-permeable gaskets 434, 436. Accordingly, the fresh air 318, which is at a higher pressure than the air provided within the drying chamber 408 due to the operation of the process air fan 410, is drawn into the drying chamber 408 around the ends 1108, 1110 of the rotatable drum 426 (i.e., at the drum seal gaskets 434, 436) and mixes with the heated process air 307 entering the drying chamber 408 via the drum inlet 1102.

The process air 305 (i.e., the heated process air 307 mixed with the fresh air 318) is then drawn, via operation of the process air fan 410, through an opening in the front bulkhead 430 and through the lint filter 414, with a portion thereof ultimately recirculated to the heater canister 402 via the recirculation duct 420. Because, as discussed, the recirculation duct 420 is in closed fluid communication with the heater canister 402, the recirculated process air 307 is reintroduced to the heater canister 402 but is not mixed with any fresh air at this point. Accordingly, substantially the only fresh air 318 which enters the process air circuit enters at the rotatable drum 426 (with only negligible amounts of fresh air, if any, entering at other portions of the process air circuit due to, e.g., leakage at the process air fan 410 casing, leakage around the lint filter 414, leakage at the access door, leakage at the seams of the ducting, etc.). The recirculated process air 307 is then reheated by passing over the heater 306, and ultimately is drawn once again through the process air circuit as described above.

Although in the above-described embodiments substantially the only fresh air which enters the process air circuit enters at the drum seal gaskets 434, 436, in other embodiments fresh air 318 may be drawn into the process air circuit at other suitable locations while still omitting the air inlet 201 discussed in connection with FIG. 2. For example, in some embodiments, one or more apertures (not shown) may be formed in the rotatable drum 426 such that the fresh air 318 is drawn directly into the drum 426 (and thus process air circuit) via the apertures. In other embodiments, one or more apertures or the like may be formed in other components defining the process air circuit, such as, e.g., in one or both of the manifolds 424, 438 or one or both of the bulkheads 428, 430. For example, one or more of the rear manifold 424, the rear bulkhead 428, the drying chamber 426, and the front bulkhead 430 may be configured (by, e.g., including the apertures or the like) such that substantially the only fresh air 318 which enters the process air circuit enters the process circuit, in an airflow direction of the process air, at a location after the heater canister 402 but before an outlet of the rotatable drum 426 (e.g., the opening provided in the bulkhead 430). In any event the fresh air inlet (e.g., suitably configured drum seal gaskets 434, 436, apertures, etc.) will be provided at a location where a pressure of the process air, due to operation of the process air fan 410, is lower than a pressure of the fresh air 318 provided within the cabinet such that no moisture-laden process air escapes from the process air circuit into the cabinet via the fresh air inlet (unlike escaping process air 209 discussed in connection with FIG. 2).

When configured as discussed above, the hybrid vented tumble dryer 400 exhibits benefits over the known hybrid vented tumble dryer 200. For example, the dryer 400 does not include an air inlet immediately upstream of the heater canister 402 (unlike the air inlet 201 provided immediately upstream of the supply duct 202), but rather the recirculation duct 420 is in closed fluid communication with the heater canister 402. Accordingly, even if over time one or both of the front drum seal gasket 434 and the rear drum seal gasket 436 begin to wear, thus allowing more fresh air 318 to enter the process air circuit around the ends of the rotatable drum 426, the recirculated process air 307 will nonetheless not escape into an interior of the dryer 400 (unlike the known hybrid vented tumble dryer 200). This configuration thus reduces the chance of damage to internal components of the dryer 400 which could otherwise be caused by condensation of the escaping process air 209. Rather, if and when the drum seal gaskets 434, 436 begin to wear, the hybrid vented tumble dryer 400 may simply “self-tune.” That is, dryer 400 will simply operate with a different air mixture (e.g., a little more fresh air 318 and a little less recirculated process air 307) without risk of moisture-laden process air escaping to the internal components.

Additionally, because in some embodiments the only fresh air 318 entering the process air circuit of the dryer 400 enters around the ends 1108, 1110 of the rotatable drum 426 at the drum seal gaskets 434, 436, an air-restriction property of the gaskets can be relaxed as compared to the traditional vented tumble dryer 100 or the known hybrid vented tumble dryer 200. More particularly, in the dryers 100, 200, the drum seal gaskets may be designed to minimize or reduce as much as possible any fresh air 118, 218 from entering the process air circuit around the ends of a respective rotatable drum. In contrast, for the dryer 400, the air-restriction properties of the front drum seal gasket 434 and the rear drum seal gasket 436 may be configured (i.e., relaxed) such that a desired amount of fresh air 318 is allowed to enter the drying chamber 408 around the ends 1108, 1110 of the rotatable drum 426. In this regard, the front drum seal gasket 434 and rear drum seal gasket 436 may exhibit less frictional resistance when the rotatable drum 426 is rotated by the motor 502 than if the gaskets 434, 436 were configured to reduce as much as possible the fresh air 318 leaking into the drum (as is with the traditional vented tumble dryer 100 and the known hybrid vented tumble dryer 200). Accordingly, the motor 502 may require less power to rotate the rotatable drum 426 than otherwise would be needed for the dryers 100, 200, thus improving overall machine efficiency.

Further, by designing the hybrid vented tumble dryer 300 such that the only fresh air 318 entering the process air circuit is around the ends 1108, 1110 of the rotatable drum 426 at the drum seal gaskets 434, 436, overall manufacturing costs of the machine may be reduced. Specifically, the dryer 400 may require less parts to form the recirculation channel 420 than the known hybrid vented tumble dryer 200, which requires, e.g., additional ducting extending to the fresh air intake 201.

The present invention has been described in terms of preferred and exemplary embodiments thereof. Numerous other embodiments, modifications, and variations within the scope and spirit of the appended claims will occur to persons of ordinary skill in the art from the review of this disclosure. 

We claim:
 1. A hybrid vented tumble dryer comprising: a drying chamber; a heater configured to heat process air entering the drying chamber; a process air fan configured to draw the process air through the drying chamber; an exhaust duct configured to exhaust a first portion of the process air from the drying chamber; a recirculation duct configured to direct a second portion of the process air from the drying chamber to the heater; and a process air circuit configured to recirculate the process air through the hybrid vented tumble dryer and defined at least in part by the drying chamber, the heater, the process air fan, and the recirculation duct, wherein the process air circuit is configured such that: the drying chamber is located between the heater and the process air fan such that the process air leaving the heater passes through the drying chamber before the process air reaches the process air fan, the recirculation duct is located between the process air fan and the heater such that the second portion of the process air leaving the process air fan passes through the recirculation duct before the process air reaches the heater, and substantially the only fresh air which enters the process air circuit enters directly into the drying chamber prior to passing through the heater.
 2. The hybrid vented tumble dryer of claim 1, further comprising at least one gasket, wherein substantially the only fresh air which enters the process air circuit enters directly into the drying chamber at the at least one gasket.
 3. The hybrid vented tumble dryer of claim 2, wherein the drying chamber is a rotatable drum configured to rotate with respect to a bulkhead of the hybrid vented tumble dryer, and wherein the gasket is located between the rotatable drum and the bulkhead.
 4. The hybrid vented tumble dryer of claim 3, wherein the gasket includes at least one of: polyester, wool, polyurethane, ethylene propylene diene monomer rubber, and polytetrafluoroethylene.
 5. The hybrid vented tumble dryer of claim 1, further comprising a recirculation air filter removably mounted in the recirculation duct and configured to filter the second portion of the process air.
 6. The hybrid vented tumble dryer of claim 5, wherein the recirculation air filter is removably accessible from an inside of the drying chamber.
 7. A hybrid vented tumble dryer comprising: a drying chamber including an inlet and an outlet, wherein process air moving through the drying chamber enters at the inlet and exits at the outlet; a heater configured to heat the process air entering the drying chamber; a process air fan configured to draw the process air through the drying chamber; an exhaust duct configured to exhaust a first portion of the process air from the drying chamber; a recirculation duct configured to direct a second portion of the process air from the drying chamber to the heater; and a process air circuit configured to recirculate the process air through the hybrid vented tumble dryer and defined at least in part by the drying chamber, the heater, the process air fan, and the recirculation duct, wherein the process air circuit is configured such that: the drying chamber is located between the heater and the process air fan such that the process air leaving the heater passes through the drying chamber before the process air reaches the process air fan, the recirculation duct is located between the process air fan and the heater such that the second portion of the process air leaving the process air fan passes through the recirculation duct before the process air reaches the heater, and substantially the only fresh air which enters the process air circuit enters the process air circuit, in an airflow direction of the process air moving through the process air circuit, after the heater and before the outlet of the drying chamber.
 8. The hybrid vented tumble dryer of claim 7, further comprising at least one gasket, wherein substantially the only fresh air which enters the process air circuit enters directly into the drying chamber at the at least one gasket.
 9. The hybrid vented tumble dryer of claim 8, wherein the drying chamber is a rotatable drum configured to rotate with respect to a bulkhead of the hybrid vented tumble dryer, and wherein the gasket is located between the rotatable drum and the bulkhead.
 10. The hybrid vented tumble dryer of claim 9, wherein the gasket includes at least one of: polyester, wool, polyurethane, ethylene propylene diene monomer rubber, and polytetrafluoroethylene.
 11. The hybrid vented tumble dryer of claim 7, further comprising a recirculation air filter removably mounted in the recirculation duct and configured to filter the second portion of the process air.
 12. The hybrid vented tumble dryer of claim 11, wherein the recirculation air filter is removably accessible from an inside of the drying chamber.
 13. A hybrid vented tumble dryer comprising: a rotatable drum; a heater configured to heat process air entering the rotatable drum; a process air fan configured to draw the process air through the rotatable drum; an exhaust duct configured to exhaust a first portion of the process air from the rotatable drum; a recirculation duct configured to direct a second portion of the process air from the rotatable drum to the heater; a first bulkhead; a first drum seal gasket located between the rotatable drum and the first bulkhead in a non-airtight manner such that fresh air can enter the rotatable drum at the first drum seal gasket; a second bulkhead; a second drum seal gasket located between the rotatable drum and the second bulkhead in the non-airtight manner such that the fresh air can enter the rotatable drum at the second drum seal gasket; and a process air circuit configured to recirculate the process air through the hybrid vented tumble dryer defined at least in part by the rotatable drum, the heater, the process air fan, the recirculation duct, the first bulkhead, and the second bulkhead, wherein the recirculation duct is in closed fluid communication with the heater.
 14. The hybrid vented tumble dryer of claim 13, wherein substantially the only fresh air which enters the process air circuit is the fresh air entering the rotatable drum at the first drum seal gasket and the second drum seal gasket.
 15. The hybrid vented tumble dryer of claim 13, wherein the fresh air enters the rotatable drum via a first airflow spacing provided between the first drum seal gasket and the first bulkhead, and via a second air airflow spacing provided between the second drum seal gasket and the second bulkhead.
 16. The hybrid vented tumble dryer of claim 13, wherein the fresh air enters the rotatable drum via a first airflow spacing provided between the first drum seal gasket and the rotatable drum, and via a second air airflow spacing provided between the second drum seal gasket and the rotatable drum.
 17. The hybrid vented tumble dryer of claim 13, wherein the first drum seal gasket and the second drum seal gasket are air-permeable, and wherein the fresh air enters the rotatable drum though the first drum seal gasket and the second drum seal gasket.
 18. The hybrid vented tumble dryer of claim 13, wherein the first drum seal gasket and the second drum seal gasket include at least one of: polyester, wool, polyurethane, ethylene propylene diene monomer rubber, and polytetrafluoroethylene.
 19. The hybrid vented tumble dryer of claim 13, further comprising a recirculation air filter removably mounted in the recirculation duct and configured to filter the second portion of the process air.
 20. The hybrid vented tumble dryer of claim 19, wherein the recirculation air filter is removably accessible at an access opening of the first bulkhead. 